from ast import operator


first = float(input("请输入一个数:"))
second = float(input("请输入第二个数:"))
operator =input("请选择运算符：+ - * /:")
if operator =='+':
    print(first + second)
elif operator =='-':
    print(first + second)  
elif operator =='*':
    print(first * second) 
elif operator =='/':
    if second ==0:
        print("除数不能为0")
    else:
        print(first / second)